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The Great White's Way Is Longer Than Thought

One shark's fast round trip from South Africa to Australia suggests more interaction between populations than was expected.

October 08, 2005|From Reuters

JOHANNESBURG — A great white shark has surprised scientists by swimming more than 12,000 miles from South Africa to Australia and back in a journey that sheds new light on the ocean's most feared predator.

The journey of the tagged female shark -- named Nicole after Australian actress Nicole Kidman -- was the first transoceanic and longest recorded trip by a shark. Experts reckon she did it for love.

"We suspect that she went for reproductive reasons," said Ramon Bonfil of the Wildlife Conservation Society based at the Bronx Zoo.

"There's plenty of food around South Africa, and she would be using too much energy to just go to Australia to feed," said Bonfil, lead author of the study published in Friday's issue of the journal Science.

Nicole's tag recorded data on time, temperature, water depth and light levels, but not whether she mated.

Bonfil attached the satellite tag to Nicole's dorsal fin Nov. 7, 2003.

More than 30 great white sharks were tagged for the study, with many of them swimming up and down the eastern coast of South Africa. But Nicole headed out for the vast Indian Ocean basin.

Bonfil said her path was remarkably straight. After veering a few hundred miles south of South Africa's coastline toward Antarctica, she arced east and northeast to Australia.

Nicole's long swim suggests that the South African and Australian populations have far more interaction than previously thought and might not be entirely separate groups.

She completed her trip in just less than nine months with what the Wildlife Conservation Society described as the fastest return migration of any swimming marine organism known.

"Although Nicole took frequent plunges to depths as great as 3,215 feet -- a record for white sharks -- while crossing the Indian Ocean, she spent most of her time, 61%, swimming along the surface," the Wildlife Conservation Society said.

Scientists thus suspect that great white sharks might use celestial cues for transoceanic navigation.

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